RALEIGH — It’s April, and the highest-profile primary contest of the year has turned predictably mean.

When a race involves an obvious front-runner — in this case, state House Speaker Thom Tillis — and a crowded field clamors to bring that person down a peg or two, eventually some nastiness is going to emerge.

The line of attack, at a time when Republican Party politics is at least a partial hostage to tea party vetting, also comes as no surprise.

Tillis, the former IBM consultant, is being portrayed by opponents as the consummate political insider, the establishment guy.

And you know about those guys. They are “them.” You can’t trust “them.”

With this worldview, political experience and success is a negative, not a positive. Attachments to some well-known political figures can be a sign of weakness, not strength.

So Greg Brannon, a tea party darling and Cary ob-gyn who is one of the most likely candidates to beat Tillis, sends out an email railing against national GOP strategist Karl Rove for his support of Tillis.

Brannon says Rove’s American Crossroads, which is prepared to spend money to boost Tillis’ prospects, is out to “CRUSH the tea party.” In the same campaign email, he calls Rove a “establishment kingpin.”

It’s an accurate description. And any GOP candidate who hopes to beat incumbent Democratic U.S. Sen. Kay Hagan will need the help of Rove or some other establishment kingpin.

Tillis’ other biggest rival in the race, Charlotte pastor Mark Harris, has started pushing the same the message.

His campaign consultant, Tom Perdue, recently called Tillis “nothing more than a typical Democrat.” A push poll conducted by the Harris campaign, asking if voters would be more or less inclined to vote for Tillis based on certain statements, included reminders about a sex scandal involving a Tillis’ staff member and a reference to him raising money from “homosexual activists.”

Perdue apparently is a bit removed from the “typical Democrat.”

Not too many typical Democrats allow abortion restrictions, private school vouchers, and constitutional amendments banning gay marriage to move through the legislative chambers that they control.